Spray booth



J. A. PAASCHE 2,788,954

SPRAY BOOTH April 16, 1957 5 Sheets-Sheet 1 Filed July 12, 1955 J INVENTOR.

ew 6.?aawe April 16, 1957 J. A. PAASCHE 2,738,954

SPRAY BOOTH Filed July 12, 1955 5 Sheets-Sheet 2 lHllIl IN V EN TOR. flaacfi' J. A. PAASCHE April 16, 1957 SPRAY BOOTH 5 Sheets-Sheet 3 Filed July 12, 1955 INVENTOR. Q. 246626 April 16, 1957 J. A. PAASCHE SPRAY BOOTH 5 Sheets-Sheet 4 Filed July 12, 1955 INVENTOR. a Jens QM April 15, 1957 J. A. PAASCHE 2,788,954

SPRAY BOOTH Filed July 12, 1955 4 5 Sheets-Sheet 5 INVEN TOR.

9' m/w q States Patent SPRAY noon} Jens A. Paasehe, Chicago, Ill., assignor to Iline Electric Manufacturing Company, Chicago, 13., a corporation of Illinois Application luly l2, 1955,' Serial No. 521,566

8 Claims. ((3.1261-) The present invention relates to a. novel spray booth and more particularly to a novel booth in which articles may be processed as by air. painting or coating or by directing various substances against the article with a blast of air in a well-known manner. The present application is a continuation-in-part of my co-pending application Serial No. 429,802 filed May 14, 1954, now abandoned.

Airfinishing booths of the type contemplated herein have been provided for the general purpose of preventing contamination of the atmosphere surrounding the article or workpiece with paint or other material being used to treat the workpiece. Such airfinishing booths have been provided with means for drawing air therethrough and for cleaning the air before it is discharged back into the surrounding atmosphere. As is wellknown by those familiar with the art, paint and like substances rapidly collect within the booth so that it is frequently necessary to clean the booth. Thus, airfinishing booths heretofore known have been unnecessarily expensive to operate and maintain since an excessive amount of labor is required to clean the booths and also since operation of the booths must be shut down during cleaning. Various suggestions have been made for solving this problem, but structures resulting from such suggestions have still been unnecessarily expensive to operate and maintain.

An object of the present invention is to provide a novelv spray booth which may be operated and maintained more economically than spray booths heretofore known.

More specifically, it is an object of the present invention to provide a novel spray booth which may be self-cleaning and which is constructed so that the necessity for cleaning is eliminated.

Another object of the present invention is to provide a novel spray booth utilizing a liquid such as water for cleaning air passing therethrough, which booth is of relatively simple and economical construction and is more efiicient in operation.

Still another object of the present invention is to provide a novel spray booth utilizing a closed liquid system for cleaning paint and the like from the air, which system is constructed so that it is compact and may be easily and economically maintained in a substantially uncontaminated condition.

A'more specific object of the present invention is to provide a novel spray booth of the type described in the preceding paragraph wherein the cleaning liquid is filtered before returning to a storage tank so as to reduce the necessity for cleaning the tank and the entire inside walls of the booth, and the liquid is filtered in a manner which permits periodic removal of a major portion of the paint sludge or the like without shutting down the spray booth.

Other objects and advantages of the present invention will become apparent from the following description and the accompanying drawings wherein:

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Fig. l is a perspective view illustrating a novel spray booth embodying the principles of this invention;

Fig. 2 is a fragmentary perspective view of the spray booth shown in Fig. l with a panel thereof removed to illustrate certain features in greater detail;

Fig. 3 is an end elevational view of the spray booth embodying the principles of this invention;

Fig. 4 is an enlarged fragmentary cross sectional ,view taken along line 4-4 in Fig. 3;

Fig. 5 is an enlarged fragmentary cross sectional View taken along line 55 in Fig. 1;

Fig. 6 is an enlarged fragmentary perspective view showing a portion of the structure in greater detail;

Fig. 7 is an enlarged fragmentary perspective View illustrating a portion of the novel air and liquid bafile structure of the present invention in greater detail;

Fi 8 is an enlarged fragmentary perspective view taken alon line 88 in Fig. 7;

Fig. 9 is an enlarged fragmentary cross sectional .view taken along line 99 in Fig. 7;

Fig. 10 is an enlarged fragmentary cross sectional view taken along line i9l0 in Fig. 7;

Fig. 11 is an enlarged fragmentary cross sectional view taken along line 11 ii in Fig. 7;

Fig. 12 is a fragmentary sectional View taken along line i212 in Fig. 14 and showing a modified form of the present invention;

Fig. 13 is a sectional view taken along line 13.-13 in Fig. 12; and

Fig. 14 is a fragmentary sectional View taken along line Z +l4 in Fig. 12.

Referring now more specifically to the drawings wherein like parts are designated by the same numerals throughout the various figures, a spray booth 20 embodying the principles of this invention includes a housing structure generally designated by the numeral 22 and defining a work chamber and an air cleaning or washing chamber IX. As shown in Figs. 1 and 5 a workpiece 28 may be positioned within the work chamber for painting or other treatment with an airbrush or spray gun 3t; and the air within the chamber 24 is drawn through an opening or passageway 32 into the cleaning chamber 26 and then discharged from the cleaning chamber by means of a fan 34 driven by an electric motor 36. The fan is located within a large duct 33 at the upper end of the cleaning chamber, and as will be understood, this duct may either open into the atmosphere or it may be connected to additional duct work, not shown, for directing the air to any desired point of discharge.

The housing structure 2?. includes oppositely disposed side walls it} and 42?. and a rear wall 44. A top panel 46 extends between the side walls in a position overlying the work chamber 4 and a hood iii closes the top of the cleaning chamber 26 and connects this chamber With the duct 38. These members of the housing structure are preferably constructed from sheet metal and are secured together so that their interior surfaces are smooth and free from flanges, nuts, bolt heads and the like so as to reduce any possibility of the accumulation of paint thereon. Each of these members of the housing structure may be made from a single piece of sheet metal but for the size of spraying booth illustrated herein these members may be formed by a plurality of sheet metal panels joined together. As an example of this latter mentioned structure reference is had to Fig. 1 wherein the side 4% is clearly shown as including a plurality of panels which are joined together by marginal out turned flanges 59. The flanges may, of course, be secured together by bolts or screws or any other suitable means andthis structure leaves the interior surfaces of the wallssmooth and unobstructed. The front of the housing structure may be left open as shown in the drawings or it may be closed by a suitable wall structure, not shown.

The work and air cleaning chambers are separated by a wall structure 54 which includesa pair of panels 56 which are removably mounted to provide easy access to the cleaning chamber for cleaning purposes. In order to mount the panel members 56 an angle iron 58 extends between and is secured to the sides 46 and 42 of the housing. Each of the panels 56 has a pair of downwardly extending finger members 69 welded or otherwise secured thereto, which finger members are adapted to fit over the upwardly extending flange of the angle iron. The upper edge of each of the panels 56 is supported by the structure shown best in Figs. 5, 6, and 7. This structure includes a sheet metal trough 62 extending transversely across the housing and having a rear wall connected with the hood 48. The trough also includes a forward wall 64 having an integral marginal portion 66 folded downwardly along and spaced from the front wall. A plate member 67 is secured to the marginal portion 66 and is spaced from the front wall 64 so that the upper edges of the panels 56 may be received and retained within the space between the front wall 64 and the plate member 67. With this structure the panels 56 may be easily mounted or dismounted merely by raising them with their upper edges beneath the trough portion 66 until the fingers 6%? clear the angle iron.

Each of the panels 56 is provided with a pair of oppositely disposed inturned flanges 68 and 7t! along its vertical edges. These flanges not only serve to strengthen and rigidity the panels but also serve to retain the panels in the desired position. Thus, as shown best in Figs. 7 and 8, the upper ends of the flanges 63 and 76 of adjacent panels are adapted to fit within a U-shaped bracket 72 welded to the front wall 64 of the trough. In addition, the lower ends of the adjacent flanges 68 and 70 fit within a slot 74 cut in the angle iron 58. The angle iron which is weakened by the slot '74 is preferably reinforced by a member '76 welded thereto. in order to retain the adjacent panels 56 together throughout their entire length and to provide a substantially airtight junction therebetween, the flangeifi of one of the panels is provided with a reversely bent marginal portion 73, whereby to form a U-shaped pocket for receiving the flange 68 of the adjacent panel.

In order to wash the air passing through the cleaning chamber 26, a pipe or conduit 89 is arranged to cross the chamber well above the opening 32 and a series of nozzles 82 are connected with the conduit for directing a spray generally downwardly and a second series of nozzles 84 is connected to the conduit for directing a spray laterally and downwardly. As shown best in Fig. 5, the nozzles 82 and 8 are arranged so that the sprays therefrom overlap each other and extend entirely across the chamber. A cleaning liquid which is preferably water with a suitable detergent is delivered under pressure to the conduit 86 by means described fully hereinbelow.

In accordance with a feature of the present invention novel and simple means is provided for insuring even distribution of both the water and air across the cleaning chamber and for insuring intimate contact between the air and water so that the air is more efliciently cleaned. This means is shown best in Figs. 2, 5, 7 and 11 and includes a plurality of baffle members 86 arranged at an acute angle to the horizontal, and at an angle to the water spray. An angle member 38 is secured to the rear wall 44 of the housing for supporting the upper ends of the baffle members 36 and the lower ends of the baflle members rest on the angle iron 58. Preferably a sheet metal bafile 90 is disposed between the baflle members 86 and the angle iron 53 so that water draining down the baflle members 86 is directed over the angle iron 58. It should be noted that the water falling from the angle iron 58 joins with water flowing down the panels 56 to form a continuous curtain so that air passing through the opening 32 is initially cleansed by the water curtain. Each of the baffle members 86 is formed from a sheet of slit and expanded metal and is corrugated or provided with a plurality of generally V-shaped sections for increasing the surface area thereof for a given width as shown best in Fig. 11. Expanded metal of the type used to make the baffle members 86 is commercially available and need not be further described. The expanded metal baflle members serve to diifuse the air passing therethrough evenly throughout the cleaning chamber and thereby promote eflicient cleaning of the arr. baffle members or foraminous screens adheres thereto and provides a covering film on all surfaces of the screen so that air passing through the multitude of openings therein is brought into intimate contact with the water cleaning solvent. As will be understood, the expanded metal baffle members or screens have numerous internal corners or edges spaced relatively closely together across their entire areas and the water sprayed onto the screens tends to accumulate at these corners or edges until it falls therefrom in the form of small droplets; Thus, the expanded metal baffle members or screens serve to provide an evenly distributed rain of water droplets in the portion of the cleaning chamber beneath the screens further to promote efiicient cleaning of the air. Since, as pointed out above, substantially all surfaces of the slanting expanded metal baffle members or screens are covered by a film of water running to the front of the booth joining with the overflow water from the panels 56, any paint in the air passing therethrough will not adhere to the screens so that the screens are automatically cleaned without manual cleaning and waste of time.

The air passing upwardly through the water sprays while being cleansed of any paint or like material may contain a considerable amount of water vapor and, therefore, baflle means 94 is provided for removing excess water vapor from the air. This baflle means includes a plurality of sheet metal angle members 96 which are welded together and positioned relative to each other as shown best in Figs. 7 and 9 to provide a pluralityrof tortuous paths for the air. The bafile members 96 are supported at their rear ends on an angle member 98 which is welded or otherwise secured to the rear wall 44 of the housing and they are supported at their forward ends on a similar angle member T09 which is mounted between the side walls of the housing. As best shown best in Fig. 7 the angle member 100 like the angle member 58 described above is provided with a slot 102 for receiving the flanges of the panels 56 and the angle member 109 is reinforced by member 104 which is welded thereto. In addition finger members 105 are welded to the panels 56 for detachably connecting the panels to the angle member lllil. As the air passes upwardly through the tortuous paths of the baffle means 94 the water vapor in the air is brought into contact with and clings to the sheet metal angle members 96. After suflicient moisture has collected on the sheet metal angle members droplets will form which fall onto the expanded metal balfle members or screens whereby to prevent any water being exhausted to the atmosphere.

In order to prevent paint and the like from adhering to the interior surfaces of the housing side walls 40 and 42 within the work chamber and from adhering to the surface as of the panels 56 means is provided for direct ing a substantial film or curtain of water over the surfaces. This means includes the above described trough 62 and similar troughs 106 and 103 arranged along the upper edges of the sides 40 and 42 respectively. Water is introduced into these troughs at such a rate that they are continuously overflowing and continuous films or curtains of water pass from the troughs and downwardly along the surfaces of the sides 4! and 42 and the panels 56. As shown best in Figs. 1, 5 and 6 water is introduced into the trough 62 through conduits 110 and 112 and a In addition, the water sprayed against the expanded.

discharge nozzle or conduit 114, which conduits are connected with one endof the conduit 83 A valve 115 is provided for controlling the flow of liquid through the conduit 110, which valve is operated by a handle 117 conveniently located at the front of the booth through a connecting rod 119. The discharge conduit or nozzle 114 is preferably located adjacent the middle of the trough 62 so as to promote even distribution of water throughout the trough and has a discharge end 116 'cut at an angle to provide a relatively large discharge opening as compared to the diameter of the conduit. The relatively large discharge opening reduces surging of the water and further promotes even distribution of the water throughout the length of the trough. The efiect of the water surging into the trough from the discharge conduit is positively overcome by a spreader plate 11% which is shown best in Figs. 5 and 6. The spreader plate includes a horizontal section 120 through which the conduit 114 extends and a vertical section 122 disposed along the forward side of the conduit 1 4, and having a rearwardly bent lower marginal portion T123. referably a rubber gasket 124 is provided for sealing the opening through the horizontal section through which the conduit 11-: extends. The opposite ends or" the spreader plate are held in positions spaced from the forward wall of the trough by means of bolts 12d which are threaded into nut members welded to the trough or by any other suitable means. With this structure it is seen that the spreader plate positively prevents the water from surging directly from the conduit or nozzle 11.4 and over the mid portion of the trough forward wall, but to the contrary the water must first spread laterally toward opposite ends of the trough, so that all portions of the trough are substantially equally filled and the curtain of water flowing from the trough will be substantially in smooth mirror-like form and uniformly distributed across the entire widths of the panels 56.

Water is supplied to the trough 1% through a conduit 128 an a discharge nozzle or conduit 1 9, which conduits are connected to the conduit 11% as shown best in Fig. l. The discharge conduit 139 is preferably identical to the discharge conduit or nozzle 11% described above and a spreader plate 132 is associated with the discharge conduit or nozzle 13%? for distributing the water evenly throughout the length of the trough 1%. The water is similarly delivered to and spread in the trough 1% by a discharge conduit or nozzle 134 and a spreader plate 136. The discharge conduit or nozzle 13a is connected by conduits 13% and 14b to the same source of water under pressure to which the conduit so is connected. The flow of water to the nozzle 134 may be controlled by a valve 141 located in te conduit 138' and operable by means of a handle 143 and connecting rod 14-5.

A reservoir for water to be supplied to the various nozzles described above is provided by an elongated 142 which has a major portion thereof positioned beneath the air cleaning chamber so as to reduce the floor space required for the apparatus and which also has a portion 144 extending laterally from the side 40 of the housing. A pump 146 has its inlet side connected to the interior of the tank by means of a conduit 148 and its outlet. side connected to the conduit 86 through conduits 156 and 152. in addition the conduit 14% is connected to the conduit 15%) through a suitable coupling member. The pump 146 may conveniently be driven by an electric motor 15 so that the filtered water is delivered to the various nozzles and particularly the nozzles 82 and 84 under considerable ressure. A gauge 156 may be connected to the conduit 80 so that the pressure of the water delivered to the nozzles 82 and 3 may readily be determined. The water discharged to the various nozzles is returned to the reservoir in the manner described below but, as will he understood, some water will be lost as a result of evaporation. The water within the reservoir or tankis preferably kept at a constant level and this is accomplished by means of a float valve 158 which is inserted in a conduit 160. The conduit 160 is connected to any suitable source of water, not shown. In order to prevent the tank from accidentally overflowing an overflow pipe 162 is connected between the top of the tank and a drain pipe164 as shown best in Fig. 3. In addition the drain pipe is connected through a valve 166 to the bottom of the tank so that upon opening the valve the tank may be completely drained for flushing when clean Water is needed or any other desired purpose.

As will be understood, the water flowing down the side walls and panels 56 of the housing structure and the water sprayed into the air cleaning chamber becomes relatively heavily contaminated with the paint or other material used to paint any product 28. Itis, of course, desirable that the paint or the like be separated from the water so that only relatively clean water is recirculated by the pump. In somewhat generally similar spray booth structures heretofore suggested the paint has been separated from the water by allowing the water to fall directly from the cleaning chamber into a large tank and allowing the paint and the like to settle to the bottom of the tank. However, this heretofore known method of separating the paint from the water is not entirely satisfactory since the entire tank must be cleaned at frequent intervals and since the spray booth cannot be used while the tank is being cleaned, whereby valuable production time is lost. Therefore, another important feature of the present invention resides in the novel structure for separating the paint and the like from the water in a manner so that the tank need only be flushed clean at time of changing to clean fresh water. This novel structure is shown best in Figs, 1-5 and includes a shallow sheet metal water runway 168 underlying. the air cleaning chamber 26 and the panels 56 and overlying the entire portion of the storage tank or reservoir 142 disposed within the housing. Thus, the trough 168 receives all of the water and sludge discharged by the nozzles 82 and 34 and all of the water. flowing down the panels 56. In addition, other sheet metal troughs 170 and 172 are positioned for receiving the water flowing down the sides 40 and 42respectivelyand for delivering the Water thus received to the water runway 168. As shown best in Fig. 4, the water is discharged from the trough 168 through an opening 174 in the housing side 40 and into filter means 176 located in the tank portion 144. The filter means includes a foraminous metal container 178 which is supported above the bottom of the tank on feet or blocks 180 and a fabric bag 182 disposed within the container and removably connected to the upper edge thereof by a ring 184. Any suitable fabric which will filter paint and like particles from water flowing therethrough may be used for the filter bag 182. Since the troughs 168, 170 and 172. are shallow the water flows rapidly therefrom so that the paint and like particles are washed from the troughs and are delivered into the filter bag 182. Whenever a predetermined amount of paint or the like has accumulated in the filtering bag 132, the bag may be quickly and easily removed and in a few minutes replaced by a clean bag so that the spray booth may be operated without interruption saving costly cleaning time.

In Figs. 12, 13 and 14 there is shown a modified form of the present invention which is similar to the above described structure as indicated by the application of identical reference numerals with the suflix a added to corresponding elements. In this embodiment a plurality of filtering screens are arranged in a novel manner for filtering the water flowing from the runway or trough 168a before the water passes into. the 'major portion of the reservoir and is recirculated by the pump. More specifically, a filtering screen which may be formed from expanded metal or any other suitable material is disposed to providea continuation of the runway 168a,

and is mounted between a wall 202 of the reservoir and an imperforate partition 204 disposed within the reservoir. The screen 2199 is provided with a marginal inverted V- shape portion 296 which hooks over an upturned flange 208 of the trough 162a and functions as a water leveler. The water flowing down the runway 163a flows across the screen 260 so that a portion of the water is filtered and dropped through the screen and another portion of the water carrying the paint sludge or other contaminated material passes over the free marginal edge of the screen. The inverted V-shape section 206 of the screen levels the water flowing down the runway and the screen so that the water or cleaning liquid will cover the entire screen 209 uniformly. Thus, the screen 200 is continuously flushed by the cleaning water which will carry away any deposits of sludge on the screen and prevent clogging of the screen.

Beneath the filtering screen 260 are additional filtering screens 21a and 212. The screen 210 is removably disposed between pairs of guides 214 and 216 respectively secured to the tank wall 202 and the partition 204, and the screen 212 is. similarly removably disposed between pairs of guides 213 and 22. Also mounted between the wall 202 and the partition 204 is an imperforate bafile 222 arranged so that it is adjacent to but spaced from the filtering screen 210 and also spaced from the outer end of the reservoir or tank. The bafile 222 directs the cleaning liquid flowing over the end of the filtering screen 206 downwardly along the screen 210 so that the screen 216 is continuously flushed to prevent clogging thereof.

It should be noted that the screen 210 and the bafile 222 are inclined from the vertical downwardly and in the direction of flow of the cleaning liquid so that the clean liquid will pass along the underside of the screen. Thus any sludge or the like filtered from the water by the screen 210 has a tendency to fall from the screen under the influence of gravity as well as a result of the above mentioned flushing action of the liquid. The cleaning liquid flows as indicated by the arrows in Fig. 12 so that .a portion thereof passes through the filtering screen 210 while another portion swirls around in eddy currents and carries the sludge away from the screen, and a considerable portion of the sludge fiows to a surface of the cleaning liquid in the tank behind the bafile 222 has indicated at 22 This floating sludge may be easily removed by an operator with a dipper at any desired time without interrupting the operation of the spray booth. Since most of the sludge can be removed in this manner it will be necessary to shut down the spray booth for cleaning the filtering screens only at infrequent intervals. Furthermore, the removable filtering screens can be replaced, when necessary, with clean screens very rapidly so that the operation of the spray booth need not be unduly interrupted.

The cleaning liquid which has been filtered by the screens 2tlfi21ll passes through the filtering screen 212 and into the main body of the reservoir, which screen serves to remove any small quantity of sludge that may have passed through the screens 2% and 210. The screen 212 is also inclined with respect to the vertical so that the sludge may fall therefrom by gravity. The upper end of the screen 212 is disposed adjacent the end of the runway 1581;. so that all of the liquid passage through the filter screen 2% will also flow through the screen M2. The filtered water in the main body of the reservoir tank is drawn by the pump to the inlet l liia'which is located in the outer end portion 144a of the tank and outside of the partition 204 so that only filtered liquid or water is recirculated through the system. In order to prevent any of the contaminated water from flowing from the runway 168a into this portion of the tank, the trough has an inclined portion 225 for directing the water or liquid so that all of it will flow over the filter screen 200.

' From the above description it is seen that the present invention has provided a novel spray booth structure which is fully capable of satisfying the objects heretofore set forth. More specifically, it is seen that the present invention has provided a novel spray booth structure which need be cleaned infrequently so that maintenance and operation costs may be substantially reduced. In addition, it is seen that the present invention has provided a novel spray booth which is of simple, compact and economical construction and which is more efiicient in operation, so as to provide great savings of time and labor.

While the preferred embodiments of the present invention have been shown and described herein, it is obvious that many structural details may be changed without departing from the spirit and scope of the appended claims.

The invention is claimed as follows:

1. A spray booth comprising housing means providing a work chamber, a liquid reservoir having a major portion thereof disposed beneath said housing means, means for withdrawing liquid from said resewoir and delivering the liquid into said housing means for removing any contaminating material such as'paint and the like from said housing means, shallow runway means covering said major portion of the reservoir for receiving said delivered liquid and any contaminating material carried thereby, said reservoir including a second portion extending beyond an end of said runway means, and filter means including a first filter screen-like member disposed to provide a continuation of said runway means and overlying a part of said second reservoir portion, a second filter screen-like member traversing said second reservoir portion and disposed beneath a free margin or" said first filter screen-like member, and a third filter screen-like member traversing said second reservoir portion and disposed beneath a junction of said runway means and said first filter screen-like member, whereby a portion .of the liquid flowing from the runway means flows across said first filter screen-like member and over the free margin thereof and carries a major portion or" any contaminating material therewith and subsequently flows successively thnough said second and third filter screen-like members, and another portion of the liquid drops through said first filter screen-like member and flows through said third filter screen-like member into the major portion of the reservoir.

2. A spray booth, as defined in claim 1, wherein said second filter screen-like member is inclined from the vertical downwardly and in the direction of flow of liquid therethrough so that liquid passes through an underside thereof whereby any contaminating material may drop therefrom by gravity.

3. A spray booth, as defined in claim 1, which includes bafile means traversing said second reservoir portion adjacent to and spaced from the free margin of said first filter screen-like member and said second filter screen-like member for directing the liquid flowing over said free margin downwardly along said second filter screen-like member to flush any contaminating material from said last mentioned filter screen-like material.

4. A spray booth, as defined in claim 1, which includes water leveling means at a junction between said runway means and said first filter screen-like member to promote complete covering of the first filter screen-like member with the liquid flowing from the runway means so that said last mentioned filter screen-like member will be continuously flushed by the liquid to prevent clogging thereof by the contaminating material.

5. A spray booth comprising housing means providing a work chamber having opposite side walls and a back wall, an air cleaning chamber behind said back wall, and an opening between said chambers so that air may flow from said work chamber through said air cleaning chamber, means for directing curtains of liquid downwardly along said walls of said work chamber, said last mentioned means including troughs extending along upper portions of each of said walls, nozzles for directing liquid into each of said troughs, and spreader means within each of said troughs adjacent said nozzles for distributing liquid emerging from the nozzles throughout the length of the troughs, a shallow runway beneath a lower edge of said back wall for receiving liquid flowing down the back wall, additional shallow runway respectively associated with said side walls and connected with said first mentioned shallow runway for receiving liquid fiowing down the side walls and directing the liquid into said first mentioned shallow runway, a reservoir beneath said air cleaning chamber, said first mentioned shallow runway extending across said air cleaning chamber and covering a major portion of said reservoir, removable filter means disposed in a relatively small portion of said reservoir, and said first mentioned shallow runway having a discharge opening positioned for directing the liquid into said filter means so that all liquid is filtered before flowing into the major portion of the reservoir.

6. A spray booth, as defined in claim 5, which includes means for drawing air from said work chamber, beneath said back wall and through said cleaning chamber, means above said lower edge of said back wall for spraying air cleaning liquid into said air cleaning chamber, and wherein said back wall includes a plurality of removably supported juxtaposed panels with adjacent margins of the panels terminating in abutting flange means, one of said flange means having a substantially U-shaped transverse cross section and receiving the other of said flange means to provide a joint between the panels which resists the passage of air therethrough so that substantially all of the air will pass beneath the lower edge of said back wall and beneath said spraying means.

7. A spray booth, as defined in claim 5, wherein said reservoir includes a relatively small portion separated from said major reservoir portion by said filter means and disposed outside of said housing means for receiving contaminated liquid from said runway means, which liquid subsequently passes through said filter means to said major reservoir portion so that the contaminated material collects in said relatively small reservoir portion to facilitate 10 removal thereof from the reservoir without unduly in terrupting operation of the spray booth.

8. In a spray booth structure, the combination comprising a reservoir adapted to be positioned within a spray booth housing for containing a supply of liquid to be delivered into the housing for removing contaminating material such as paint and the like from the housing, shallow runway means trversing and covering a major portion of said reservoir for receiving liquid delivered to the housing, said reservoir having a second portion extending beyond a discharged end of said runway means, and filter means including a first filter screen-like member disposed to provide a continuation of said runway means and overlying a part of said second reservoir portion, and general- 1y upright filter screen-like means traversing said second reservoir portion beneath said filter screen-like member and in part disposed beneath a junction of said runway means and said filter screen-like member, whereby a portion of the liquid flowing from said runway means flows across said filter screen-like member and over a free margin thereof and carries a major portion of any contaminating material therewith and subsequently flows through said generally upright filter screen-like means into the major portion of the reservoir, and another portion of the liquid drops through said filter screen-like member and through a portion of said generally upright filter screen-like means into the major portion of the reservoir.

References Cited in the file of this patent UNITED STATES PATENTS 1,737,313 Kamrath Nov. 26, 1929 2,008,800 Somers July 23, 1935 2,086,514 Saunders et a1 July 6, 1937 2,217,345 McGraw Oct. 8, 1940 2,583,390 Paasche Jan. 22, 1952 

